I also have to ask about the birds on the sheath, I haven't seen that before.
In the 2nd pic you can see the fit into the sheath, it's almost perfict. but I will take bettwer pic's of it. After I was looking at the blade I can see the naga was added but it still looks to me as if it was done at the time of making the blade?
In looking more at the sheath and on the site of
http://perso.wanadoo.fr it looks like it could be a WARANGKA LADRANG, MADURA (IRAS) I know the one pice is broken off and maybe the other site I dont remember. But I will look next time and take a pic.
Well more pics to come later.